Antiferro-quadrupole state of orbital-degenerate Kondo lattice model with f^2 configuration

Abstract

To clarify a key role of $f$ orbitals in the emergence of antiferro-quadrupole structure in PrPb${}_3$, we investigate the ground-state property of an orbital-degenerate Kondo lattice model by numerical diagonalization techniques. In PrPb${}_3$, Pr${}^{3+}$ has a $4f^2$ configuration and the crystalline-electric-field ground state is a non-Kramers doublet ${\Gamma }_3$. In a $j$-$j$ coupling scheme, the ${\Gamma }_3$ state is described by two local singlets, each of which consists of two $f$ electrons with one in ${\Gamma }_7$ and another in ${\Gamma }_8$ orbitals. Since in a cubic structure, ${\Gamma }_7$ has localized nature, while ${\Gamma }_8$ orbitals are rather itinerant, we propose the orbital-degenerate Kondo lattice model for an effective Hamiltonian of PrPb${}_3$. We show that an antiferro-orbital state is favored by the so-called double-exchange mechanism which is characteristic of multi-orbital systems.

3 pages, 3 figures, Proceedings of Skutterudite2007 (September 26-30, 2007, Kobe)

References in corpus (3)

• Observation of Modulated Quadrupolar Structures in PrPb3
• Orbital ordering phenomena in $d$- and $f$-electron systems
• Multipole correlations in low-dimensional f-electron systems

Cited by in corpus (3)

• First-principles theory of magnetic multipoles in condensed matter systems
• Mean-field Study of Antiferromagnetic and Antiferroquadrupolar Orderings in Tetragonal CeCoSi
• Microscopic Theory of ${\Gamma }_3$ Quadrupole Ordering in Pr Compounds on the Basis of a $j$-$j$ Coupling Scheme